How to program USB-6501 in ANSI C?

[DigitalDave]

Hello all,

I've got an NI USB-6501 unit and the software which came with it; no LabView or Measurement Studio. I'm trying to control its digital outputs via DAQmx's ANSI C API functions, using Microsoft Visual C++ 2008 Express Edition. DAQmxWriteDigitalLines(), DAQmxWriteDigitalU8(), DAQmxSwitchConnect(), and DAQmxSwitchCloseRelays() look promising, but I haven't been able to get NI's sample code to compile and I don't know what device/relay name to use in the included ControlIndividualRelays.c sample program.

I'd like to be able to open and close the eight relays (digital outs) on Port 0 of this device, as can be done with NI's Measurement & Automation Explorer GUI. This probably shouldn't be so difficult, but I'm new to this and unsure how to proceed.

Thanks in advance for any assistance you can provide!

-- DigitalDave

  

[Christian Mergl]

Hi Dave,

Just go to Start>Programms>National Instruments>NI DAQ>Textbased Code Support> ANSI C Examples>Digital I/O

There you will find the right functions to use.

Christian

[DigitalDave]

Sorry, no. Of course I have already tried this, and as I noted, not only was it not clear which of four or five DAQmx functions to use, but none of the sample code would even compile.

[Christian Mergl]

Did you try to run C:\Users\Public\Documents\National Instruments\NI-DAQ\Examples\DAQmx ANSI C\Digital\Generate Values\Write Dig Port example?

The functions would be:

DAQmxCreateTask

DAQmxStartTask

DAQmxWriteDigitalU32

DAQmxStopTask

DAQmxClearTask

The other functions you mentiond are for NI Switch hardware, not for DIO.

Christian

[Seth_B.]

What error did you receive when you attempted to compile the code?

For more help with the functions, you can also check out the NI-DAQmx C Reference Help, which will explain what each of the functions does.  This can be found at Start » Programs » National Instruments » NI-DAQ » Text-Based Code Support.

The examples are divided into several different functions.  Some write ports which are a collection of lines which are individual channels on your device.  Some of the examples continuously update the values, while some just update the values once.

Regards,